For those of you considering yah unstable and skype not that private, there is also ICQ: https://icq.com/windows/en
Surprisingly, it is still used both in professional and private areas. It has a simple interface, and, in my experience (some years ago), it never went unstable or anything.
Give it a try, I would

Skype is as private as you make it, right? I mean, I wouldn't use the same Skype account for naughty chats and business.